Rastafarianism is a creed that hides its humane spirituality under warlike metaphors. Since his death in 1981, Bob Marley has been both Rasta saint and commander in chief. His eminence came from his universality, and his best work, from “No Woman No Cry” to “Redemption Song,” fused anger with tenderness and incantational melodies. This posthumous album inevitably falls far short of his best. It was compiled by his wife, Rita, and Island Records chief Chris Blackwell from three reworked Jamaican singles (“Blackman Redemption,” “I Know” and “Trench Town”) and from studio tracks dating back to the 1979-1980 sessions between the Survival and Uprising LPs. Called Confrontation, in line with Marley’s wish to have a trilogy of linked conceptual names, the album is diffuse in its impact. Marley’s scratchy-soothing vocal style and inimitable phrasing dominate the songs, properly and sometimes powerfully, but the charged atmosphere that came about when he led the Wailers and the magically responsive backup singers, the I-Threes, simply can’t be duplicated by overdubs. Confrontation is an album of numerous small pleasures — the water-bug delicacy of “Jump Nyabinghi,” the forceful insight of “Buffalo Soldier,” the gospel-like adamancy of “Rastaman Live Up!” — and it is a valuable, welcome document. But the magical part of Marley’s rich legacy is best sought out on previous releases.